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New Member

I have a hot water heater at a rental house that has some sort of secondary pressure valve coming off the supply line from the house and the top of the hot water heater. Is anybody familiar with this set up? It is leaking at a steady pace at the side of the house, I’ve tested the house pressure and it is within specs. I am a rookie DIY’r so not technically familiar with how this interacts with the
Hot water heater or the traditional pressure relief valve (which is not leaking). I will post a few pictures I had taken when I did a previous repair, to show the part I am taking about. It has a small coper pipe coming off of it, not sure the exact size approximately 1/4”.

If anybody can help me identify this part and if what would cause it to be leaking? Ideas on how to fix it?

Not really sure WHY it's there, but it looks like and adjustable pressure relief valve. I have seen similar relief valves, but are usually 1/2" .

can you read the tag hanging on the threaded connection into the ball valve?
any numbers or names on the valve.
maybe it was a lower pressure relief used instead of an expansion tank to deal with thermal expansion. you have a safety valve on the heater so I would just remove it and plug it.

in Massachusetts you are require to install a temp/pressure relief valve
and a vaccum relief valve on the cold inlet never seen that setup before

i just looked at the pic again maybe its a bleeder so when you shut down a particular area you can remove the water ......is there a slotted screw driver head you can shut off

vaccum relief is there incase there is reverse flow....in the case of a fire...the trucks have pumps and i think
the theory is when fighting a fire lots of water is being drawn to that area so it could implode the tank i guess it may never happen but the reasoning is that it could

New Member

the house is a rental and i won't have access for at least a week to get a picture of the valve, tenent is out of town, i noticed the leak when doing some outside work. The house is plumbed with PEX, if this is a low presure relief valve, is this something common or required with PEX. The house is located in Hesperia, CA and i have seen another house with this same set up, different development, so posssibly a local building code requirement. I can easily remove and plug it, but would be concerened if it is needed to protect PEX from thermal expansion?

Well-Known Member

All I know is if its leaking from the t&p valve, then you must check the pressure it must not exceed 80 psi, next is the gas control valve it might get stuck and over heat the water causing it too open and leak out, check this by inspecting the temperature and visualizing the burner forming off, last will be to replace the t&p it self, (thats usually a sympton, not the root cause)